Presentation Authors: Satoshi Ogawa*, Takeshi Ishimura, Yuzo Nakano, Masato Fujisawa, Kobe, Japan
Introduction: Glomerular enlargement caused by glomerular hyperfiltration is one of the etiologies that affects graft function after kidney transplantation (KTx). Although the glomerular volume in baseline biopsies is reported to be predictor of graft function, the significance of change in glomerular volume in long-term period after KTx is unclear. We investigated changes in glomerular volume in protocol biopsies obtained from patients who underwent KTx and examined its correlation with subsequent graft function and other clinical factors.
Methods: We enrolled 37 patients who underwent KTx between 2006 and 2012 at Kobe university hospital. All these patients underwent protocolbiopsy at 1 hour, 1 year, and 5 years after KTx and had stable graft function with an estimated glomerular filtration rate (eGFR) > 30 mL/min at 5 years after KTx, and without an episode of rejection or any complications that affect graft function. Glomerular area (GA) was defined as the area described by the outer capillary loops of the tuft and was calculated by Image J software (National Institutes of Health, Bethesda, MD, USA) and the mean value of glomerular area in whole specimen was used for this study. Then mean glomerular volume (Vg) in the specimen of protocol biopsy at 1 hour, 1 year, and 5 years after KTx (Vg1h, Vg1y, Vg5y, respectively) was estimated according to the Weibel and Gomez method as: Vg=GA3/2Ã—1.38/1.01 We evaluated the changes in Vg and investigated the correlation of Vg1h, Vg1y, Vg5y with eGFR and amount of daily proteinuria at 1week, 4 weeks, 1 year and 5 years after KTx.
Results: The Vg increased signiÃ¯Â¬ cantly after kidney transplantation (Vg1h = 4.3 Â± 1.8 Ã— 106 Î¼m3, Vg1y = 5.3 Â± 2.1 Ã— 106 Î¼m3 [p < 0.001, Vg1h vs Vg1y], Vg5y = 6.1 Â± 2.3 Ã— 106 Î¼m3 [p < 0.001, in Vg1y vs Vg5y]). Neither Vg1y nor Vg5y was correlated with estimated glomerular filtration rate (eGFR) or proteinuria; Vg1h was correlated with eGFR at 1 week after KTx (R = 0.40, p = 0.016).
Conclusions: After KTx, the transplanted glomerular volume was observed to increase over time. Glomerular volume at the time of transplantationwas correlated to renal function at early transplantation.